[Galaxy S II Android Development] Saber:
Since the wiki for our device hasn't been updated yet, here are a list of some issues on CM13:

Issues marked with red are recent issues you will experience in any current build of CM13.

Ongoing issues:

MX Player can not use HW+ decoder. Instead, use HW or SW decoder. The developer of MX player is working on a fix.

Cyanogenmod OTA Updater sometimes can be buggy. MD5 errors, download errors, installation errors. Although it is working fine for most people, I still recommend just to flash manually via recovery!!!

Internal storage and external storage is not labelled correctly and has a random name. This is not a bug but a feature of one of the mounting ways of MM.

Screenrecorder works for some users, however it seems that you can not playback them on your phone. Workaround: Play the videos using your PC.

Some apps may have trouble detecting internal/external storage.

Some bluetooth devices may not behave properly or connect

Multiple issues with F2FS. Please note that this FS is still relatively new for our device so bugs are likely to be experience. Stay on ext4 for best stability!

Some people have reported that they have lost connection to their mobile network. This usually can be fixed by resetting APNs. If this doesn't help, you may need to downgrade back to stock 4.1.2 ROM.

MMS video file (.3pg format) will not play on the default video player. Workaround: Play the video through MX Player on SW renderer.

Hardware button is always on until screen is switched off. Workaround: After installing the BLN MOD and synapse, you can control the timeout values.

You may experience reboots when you receive phone calls

More to be added later

Fixed issues:

(from latest issue solved to earliest)

Cyanogen Recovery can not mount internal and external storage. You can not flash zips via internal or external storage. ADB sideload or other methods of flashing can be used instead. Fixed in nightly 20161005

Battery Percentage Incorrect and Causing Constant Low Battery Warnings. Fixed in nightly 20160818

As of the 20160722 nightly, decryption of /data partition is broken. Keyboard can't be switched to enter digits. Fixed in nightly 20160724

As of the 20160722 nightly, setup wizard is broken. When you press next, the notification bar drops down instead of the next screen showing. Fixed in nightly 20160724

Some people have reported that the youtube app (play store version) displays green lines during playback.

Front camera errors in recent builds

Phone dialer is currently broken Workaround: Use google dialer from Google Play Store

Live lockscreen has multiple issues being experienced in recent builds.

Nightly 20160326 is experiencing Google Play Launcher FCs. Please stay on a earlier build until this is fixed. Fixed in nightly 20160329

People who are using a non-english language may experience Clock app FCs. This problem is under investigation. Update: Fixed in nightly 20160325

Doze feature can not optimize any apps. This is not a bug, doze is disabled on our device! Please ignore this menu! Update: Fixed in nightly 20160325. Note: This is the app standby feature that is now working and not motion sensor doze!

Nightly 20160323 is experiencing CM file manager FCs Fixed in nightly 20160325

Nightly build 20160216 is currently affected by the no signal bug and dialer issues. Update: Calling issues have been fixed in nightly builds 20160218 or newer. If you are on build 20160216, you should update immediately to fix this issue.